Cooling systems in which air or liquid refrigerant is circulated are widely known. For example, in a cooling system that uses liquid refrigerant, the liquid refrigerant is circulated by a pump, heat generating bodies are cooled by a cooling device, and heat is rejected by a radiator. Furthermore, a configuration in which liquid refrigerant is boiled in a cooling device, thereby improving the cooling capacity, is disclosed (for example, see Patent Literature 1).